Cooling Systems & Electrolysis

Not sure of other models but '67-'69 cuds's already have a factory ground strap on the heater core.
Yep, and little ground strap from chassis the engine block but that still wasn't nearly enough ground path. Try this on... 1st 67 B'cuda we bought was a slant 6 notch, in summer 1981. I Looked it over, drove it, traded for it. First ride out after dark I realized this was the weakest charging system I had ever owned. Stop at a red light and headlights would dim, sit long enough and turn signals would slow. Amp gauge says discharge, dash lights dim, heater blower slower, but... This old girl doesn't have a spec of rust anywhere.
So as time has went on, I find a lot more ground wires on the new cars with all their electronics. Their aluminum radiators hold up much better than the rubber seals at plastic tanks. I have 2 1996 Camrys here with nearly 300k miles and neither has needed a heater core.
To this day I still wonder did lesser positive ions traveling through that 67 chassis help save it.